What is the shutdown command in Linux?
Overview
The shutdown command is used to halt, power off, or reboot the system.
Syntax
shutdown [OPTIONS...] [TIME] [WALL...]
- A time string may be used as the first argument, which is usually
now. Before shutting down, this may be followed by a wall message delivered to all logged-in users. - The time string can be in the format
hh:mmfor hours or minutes, which specifies the shutdown time in a 24-hour clock format. - The time string might also be in the syntax
+m, which refers to the number of minutes (m) fromnow. nowis an alias for+0, which is used to force an immediate shutdown.- If no time argument is given, then
+1is the default, meaning the system shuts down in 1 minute.
Note: To specify a wall message, a time argument must be specified.
The different options available are as follows:
| Option | Description |
|---|---|
--help |
Prints help text |
-H or --halt |
Halt the system |
-P or --poweroff |
Power-Off the system |
-r or --reboot |
Reboot the machine |
-k |
Write the wall message without halt, power-off, or reboot the machine |
--no-wall |
Do not send wall message before halt, power-off, or reboot the machine |
-c |
Cancel a pending shutdown |
Example Codes
The command below sends a wall message to all logged-in users before shutting down:
shutdown 'Hello Users! System Shutting Down'
The command below shuts down the system at 4:30 PM. The command takes the time argument in a 24-hour format:
shutdown -h 16:30
The following command restarts the system with a wall message at 4:30 PM:
shutdown -r 16:30 'Restarting System. Save your work'